Transcript for Steven and Cary Stayner: 2 brothers' horror and heroism
Yosemite, California, one of the most stunningly beautiful places on Earth. And the backdrop to one of the darkest, most horrific stories of two brothers. One who was kidnapped for seven years, the other who would become a serial killer. Is this sanctuary would turn out to be the very setting where Kerry's murderous demons would be unleashed. Reporter: It began with a kidnapping weeks before Christmas, 1972. Steven is kidnapped by Kenneth parnell. Kenneth parnell stops the car and goes to a pay phone and tells Steven, I I just smoke your parents, they no longer want you. He said you're going to be my son. He kept giving him this cough syrup to sedate him. Steven stainer had a new father figure and it was Kevin parnell who by day was his father and by night was his rapist. Reporter: Parnell moves around with Steven, settling in a small California town about five hours north of Steven's hometown of mercer. Parnell told him his name was going to be Dennis parnell. And he enrolled him in school. Reporter: More than five years have gone by, but Dennis parnell has not forgotten he's actually Steven stainer. His family has not forgotten him either. His older brother Kerry deeply affected. Kerry was very upset. Maybe he had some guilt, because I think he was supposed to be with his brother. Reporter: Kerry shows signs of disturbing behavior. He had a compulsion of trying to get close to women or be sexual with them but was unable to develop any interpersonal relationships with any women. Reporter: After seven years with Steven, parnell starts looking for a new, younger boy. In February 1980, he pays a high school kid to help him kidnap 5-year-old Timothy white. Steven watched Timmy suffer from this separation from his family for two weeks and decided, finally, that he had to do sk about it. Reporter: When parnell goes to work, Steven hitchhikes with Timothy to the town of ukiah, going directly to the police station. But when he arrives at that police station, he says something that will be embedded in the public consciousness forever. I know my first name is Steven. That's the title of the book. It became a television movie, and it made Steven famous. This is Steven today. He is holding 5-year-old Timothy white. Steven was a national hero. He returns to Merced triumphant. Good morning, Steven and Mr. And Mrs. Stainer, and Steven, how's it feel to be home? Feels great. Did you remember your parents well? Um, they didn't change that much. I recognized them when I got out of the car? What about your brothers and sisters? They changed a lot. I never recognized either one of them. Reporter: Parnell never sands trial on the kidnapping case. He is caught attempting trying to solicit a 4-year-old boy. He's given a life sentence, dies in prison. Steven goes on to work menial jobs, get married and have two but then at age 24, Steven is quilled while riding a motorcycle. His unexpected death another blow to older brother Kerry. This rage is starting to bubble up. Kerry has a couple of nervous break downs. One was fairly violent. He stated he felt like it jumping in the truck, driving it through the shop, killing the boss and everybody in the office and then torching the place, and that's when I told him he needed to go see a doctor. Reporter: He enters a mental facility but doesn't stay. He eventually makes his way to yosemite, landing a job as a handy man at the cedar lodge north of the park. He sees an opportunity to act out his sick fantasy. In one of the farthest lodges are three guests, three women, one visiting from Argentina. Kerry knocks on their door, tells them he's maintenance and needs to fix a leak. Go to the bathroom, I pulled my gun out. Reporter: About a month later, a burned car is found about 60 miles from the cedar lodge, the remains of two bodies found in the trunk. I knew from the very beginning that my girl was there. How? I don't know. Don't ask me. Just felt. Her mother's intuition was sadly correct. It was silvina in the trunk of that car. Then the big mystery was, where's Julie? Reporter: Investigators get a map in the mail. Earlier this afternoon, investigators discovered the body of a homicide victim. Body of Julie sun was identified early in the week. Reporter: Authorities would take two brothers with violent back grounds into custody in connection with the murders of the three women. People wanted to believe they were the right people in custody. But they weren't the right people. He was still working here at the lodge, still living here on the premises. He was still an active member of the community. Didn't really see him as a suspect. He didn't raise alarm bells for Reporter: That summer, Kerry finds his next victim, 26-year-old Joey Armstrong, a naturalist working at yosemite, living on the west side of the Seemed like she was alone. He gets out his backpack. He's got a gun, he's got duct tape, he's got a knife. He's standing somewhere in this vicinity, and he's talking to her. Pulled out the gun, put it to her head, she turned around, freaked out. I told her to go inside. Reporter: Authorities soon find Joey's body, in a stream near her cabin, decapitated. This was just as grisly a scene as you can possibly imagine. He left virtually no evidence at the first scene, he knew he had left a very easy trail for investigators. Reporter: Someone spotted Kerry's distinctive car. Authorities set up a man manhunt for him yesterday. Now Kerry stainer realizes he has to get out. Reporter: He ends up at a nudist community where he strikes up a conversation with someone who recognizes him from news story. I immediately picked up the phone and called FBI and told them I knew where this person Reporter: The FBI agent task Walt Disney picking up Kerry. He stands up and puts his hands up. Reporter: At the FBI office, Kerry starts unraveling. He was talking about some very grisly things, as if he was reading a soup label. Reporter: Stainer confesses to Joey's murder, then says he has more to share. Juli was very calm. Reporter: He describes killing months before. I laid out the blanket. I slit her throat. Reporter: Taped confession in hand, the FBI asked Kerry to take them to where he carried out the murders. With the recovery of the duct tape and the watch and the knife, which was the murder weapon, now we're talking evidence. Reporter: Kerry stainer was found guilty and sentenced to death. As far as I know, he's never talked to anyone about the effect Steven might have had on his crimes. I'm not sure there is any direct cause and effect. Steven could have grown-up normal, happy and healthy and Kerry could have still been a serial killer. Reporter: Now 57, Kerry stainer will spend the rest of his life even California's death row.
This transcript has been automatically generated and may not be 100% accurate.